That’s what Ray Bradbury thinks of cloning. One of America’s great science-fiction writers doesn’t believe it will ever catch on.

He also doesn’t care to be called a science-fiction writer, even though it’s a tag he’s worn for most of his life. “I write fantasy,” says the 82-year-old author of “The Martian Chronicles.” “Science fiction is the art of the possible. I imagine the impossible.”

Yet this October marks the golden anniversary of the one book in his corpus that he will admit is science fiction: “Fahrenheit 451.” Half a century after its publication, it remains a favorite of teachers who assign it to English classes and librarians who appreciate its celebration of literacy as the hallmark of civilization.

The public loves it, too. Last year, “Fahrenheit 451” reached No. 1 on the Los Angeles Times best-seller list after Mayor Jim Hahn made it the centerpiece of a citywide reading program. Next month, Ballantine will release a special 50th-anniversary edition.

Mr. Bradbury has written some 30 books, more than 600 short stories, and countless numbers of poems, essays and screenplays. Even as an octogenarian, he gets up every morning and spends a few hours composing. His most recent novel, “Let’s All Kill Constance,” came out in January to mixed reviews. A new collection of 100 short stories is slated for release in August.

Amid this prodigious output, “Fahrenheit 451” is the book for which Mr. Bradbury will be best remembered. Perhaps that’s because the concept is so unforgettable: In the near future, firemen don’t put out fires; they start them instead. Books have been outlawed. When they’re discovered, first responders hurry to the scene. The title refers to the temperature at which paper burns.

One of the paradoxes of science fiction — and a fact poorly understood by many people who don’t read it — is that much of the genre displays deep doubts about the future. Some of the finest books in the field, from Mary Shelley’s “Frankenstein” to Aldous Huxley’s “Brave New World” to William Gibson’s “Neuromancer,” regard technology as dangerous and dehumanizing.

“Fahrenheit 451” falls squarely into this dystopian tradition. Kingsley Amis said of it: “Bradbury’s is the most skillfully drawn of all science fiction’s conformist hells.”

Jules Verne is famous among science-fiction writers for predicting 20th-century technologies, such as submarines and rocket ships. Mr. Bradbury rivals him in “Fahrenheit 451.” He envisioned the popularity of headset radios, plus interactive TV and live news broadcasts.

In one scene, Mr. Bradbury’s protagonist — a renegade fireman who commits the crime of reading — tries to evade his pursuers by running down a street. He looks through the windows of the houses he passes and sees the chase being shown on television, as if he were O.J. watching himself in a white Bronco.

This kind of prognostication is remarkable for a man who verges on technophobic: Mr. Bradbury has written about space travel, but he’s never driven a car. He refused to fly in a plane until his 60s. Today, he won’t go near a computer. He wrote “The Fireman,” the 1950 novella upon which “Fahrenheit 451” is based, on a coin-operated typewriter in the basement of the UCLA library, over the course of nine days and at a cost of 10 cents every half hour. (Call it a dime novella.) He never saw the point of updating his methods, apart from buying a typewriter of his own.

Mr. Bradbury insists that the purpose of “Fahrenheit 451” was not to prophesy. “I wasn’t trying to predict the future,” he says. “I was trying to prevent it.”

In one immediate sense, he failed. In 1979, he discovered that “some cubby-hole editors” had bowdlerized his book in 98 places. One line — “Feel like I’ve a hangover. God, I’m hungry” — became “Feel like I’ve a headache. I’m hungry.” The changes first appeared in a 1967 edition for high-school students, but it wasn’t until Mr. Bradbury learned of the problem a dozen years later and complained that his publisher saw the irony of censoring a powerful anticensorship novel. “I will not go gently onto a shelf, degutted, to become a non-book,” he wrote of the incident.

Today, Mr. Bradbury is more concerned with another problem that he thinks he didn’t prevent. “There’s no reason to burn books if you don’t read them,” he says. “The education system in this country is just terrible, and we’re not doing anything about it.”

One of the often-overlooked details of “Fahrenheit 451” is that the censorship Mr. Bradbury describes was not imposed from the top by a ruthless government. Rather, it seeped up from the indifferent masses. As a villain explains: “School is shortened, discipline relaxed, philosophies, histories, languages dropped, English and spelling gradually neglected, finally almost completely ignored. . . . No wonder books stopped selling.”

Only part of that speech captures our world now, because books haven’t stopped selling. Mr. Bradbury, however, finds many of the latest ones worthless. He spends his free time reading the plays of Shaw and the poetry of Pope. “I’m learning from the past,” he says. “Few modern novelists teach me anything.”

That may be true for him. With “Fahrenheit 451” still being read and loved, though, it’s not true for the rest of us. And if we can ever figure out a way to clone Ray Bradbury, it won’t be true for our kids, either.